The clocks of the ancient Greeks

Introduction

“If you position your nose pointed towards the sun
and open your mouth wide,
you will show all passers-by the time of day”
Greek Anthology 11.418

The measuring of time is perhaps the most mysterious and at the same time the most impressive occupation of man since the beginning of his existence. Many peoples, prior to the Greeks, constructed clock-calendars, however, they were almost always consumed by the construction of larger, taller and more impressive ones (Stonehenge, Egyptian obeliscs, etc).

In ancient Greece, the country of moderation (in relation to man), science served technology in the best way possible. The Greeks invented (from 6th cent. B.C. until the end of antiquity) an amazing collection of clocks charaterised by their unrestricted imagination, their astounding variety, their high aesthetics and exceptional ergonomy; a collection which defines them as the ultimate masters of time and eternity.

In Greece (and in almost all ancient civilisations) day was referred to as the time period between sunrise and sunset and was divided into 12 hours of altering duration according to the constant increasing length of the day during the year. The year was divided into 12 parts (zodiacs) which corresponded to their homonymous asterisms. Therefore, ancient clocks counted 365 different hours (according to the day of the year) while simultaneously functioning as calendars. The reconstructed clocks which follow have been designed to operate in the geographical width of 37'' 40'.

Because of the earth's rotation around its axis, half of its spherical surface is always illuminated by the sun while the other half is shaded.

Ecliptic is the annual orbit of the sun in the celestial sphere (according to the hypothetical geocentric universal system) which forms an angle of 23" 27' with the axial rotation of the earth, an occurrence which is responsible for the appearance of the seasons and for the altering length of the day and night.

Vernal equinox: 21 March (day duration=night duration=12 hours)

Spring: 21/3 - 21/6 (92 days and 20,2 hours)

Summer solstice: 21 June (maximal day duration= 14 hours for places of geographic width of 37" 40', minimal day duration)

The hours were indicated from the shadow (on a diagramed surface) by a horizontal, vertical or oblique pointer ("gnomon"), or the mark (a bright spot) from an opening which was lit up by the rays of the sun.

Hydraulic clocks (Clepsydras)

Their initial function was based on the steady constant flow of water between two containers.